The present invention concerns an electronic watch including a case containing display means with hands and provided with a crystal made of dielectric material arranged in front of said hands, and manual control means including capacitive keys each provided with a transparent electrode arranged on the inner face of the crystal and forming a first plate of a capacitive sensor whose second plate is formed by placing a finger of the person wearing the watch on the external face of the crystal selectively opposite at least one of the capacitive keys, the control means further including detection means for detecting capacitance variations in said sensors and consequently generating control signals in the watch.
A watch of this type is disclosed for example in European Patent No. 674 247. The control device with capacitive keys allows the usual external control members to be replaced, such as push-buttons, used to control the various functions of a watch, for example time-setting, starting and stopping a chronograph or entry to a particular operating mode.
Other watches have a capacitive device for detecting the position of a watch hand, in particular for the purpose of checking and correcting if necessary agreement between the real position of the hand and its theoretical position stored in a counter of the electronic watch movement, or for detecting the position of a hand indicating the alarm time. For example, German Patent Application No. 33 17 463 and Japanese Patent Application No. 8-201537 A propose detecting variations in capacitance between the metal hands, on the one hand, and one or two series of fixed electrodes placed on the dial, on the other hand. Japanese Patent Application No. 10-10243 A further proposes that the fixed electrode may be a transparent electrode fixed under the watch crystal.